US patent 1,494,841, granted May 20, 1924 to Martin Hölken Jr. of Barmen, Germany, for an improved stretch-spinning process for making artificial silk (rayon) threads from copper oxide-ammonia cellulose solutions. The invention lengthens the air path between the precipitating bath and the hardening liquid, so most stretching happens in open air, and applies the hardening liquid to thread wound on a large reel. The specification explains the prior method, describes the apparatus shown in the drawing, and ends with three claims.

US Patent No. 1,641,588, granted Sept. 6, 1927 to Martin Hölken Jr. of Barmen, Germany, for a method and apparatus for stretch-spinning artificial silk (cuprammonium rayon). Each spinneret is fed by its own rotary gear pump instead of directly from a common pressurized supply pipe, so that thread fineness stays uniform across all spinning heads. The text describes the apparatus, with two sheets of drawings, the operation, and seven claims covering the method and the pump, pivot and articulated-arm assemblies.